Embodiments of the disclosed technology relate to a manufacture method of a thin film transistor (TFT), a manufacture method of an array substrate and a mask therefor.
Thin film transistor liquid crystal displays (TFT-LCDs) have become a popular kind of flat panel displays. Reducing the manufacture costs of TFT-LCDs becomes a main concern in development in this industry.
A thin film transistor (TFT) is an important element of an array substrate of a TFT-LCD, and generally employs a configuration with bottom gate and top contact as shown in FIG. 1A. As shown in FIG. 1A, the TFT comprises a gate electrode 12, a gate insulating film 13, an active layer 15, a source electrode 14A and a drain electrode 14B from a side of a substrate 11 in this order.
However, the inventors have found that the TFT of the configuration shown in FIG. 1A has the following drawbacks. During the operation of this TFT, the conduction layer for the charge carriers generated in the active layer when an ON voltage is applied on the gate electrode is formed at the boundary between the gate insulating layer and the active layer. In this case, the carriers (electrons) have to pass through the active layer twice to communicate between the source electrode and the drain electrode, thus the electrical properties of the TFT is influenced disadvantageously.
If a TFT with bottom gate and bottom contact as shown in FIG. 1B is employed, the carriers (electrons) merely pass through a distance up to the channel length to communicate between the source electrode and the drain electrode. In this case, since the channel length is smaller than the movement distance of the electrons of the TFT of the configuration with bottom gate and top contact, the disadvantageous influence on the electrical properties of the TFT can be avoided.
During the manufacture process of the TFT with bottom gate and top contact, a four-patterning method can be employed, in which the active layer and the source and drain electrodes are formed in a same patterning process with one same mask. However, during the manufacture process of the TFT with bottom gate and bottom contact, a five-patterning method is needed in which the active layer and the source and drain electrodes are formed in different patterning processes. Since the number of the patterning processes for the TFT with bottom gate and bottom contact is increased, the manufacture cost thereof is increased as well.